And ezra t



(No Model.)

T. A. EDISON & E. T. GILLILAND. TELEPHONE.

No. 438,306. Patented Oct. 14. 1890.

UNITED FFICE THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, AND EZRA T.GILLI- LAND, OF NEW YORK, N. Y.

TELEPHONE.

SPECIFICATION forming part of Letters Patent N 0. 438,306, dated October14, 1890.

Application filed February 19, 1886. Serial No. 192,487. (No model.)

To all whom it may concern..-

Be it known that we, THOMAS A. EDISON,

of Menlo Park, in the county of Middlesex and State of New Jersey, andEZRA T. GILLI LAND, of New York city, in the county and State of NewYork, have jointly invented a certain new and useful Improvement inTelephones, of which the following is a specification.

The object of our invention is to produce a telephone-transmitter whichshall efficiently transmit speech by variations in contact ofelectrodes, such variations being effected by the vibrations of adiaphragm against which the sound-waves are projected.

In the construction which constitutes our invention the electrodes aremoved in both directions by the diaphragm, being thrown apart when thediaphragm is vibrated forward and brought back again when the diaphragmvibrates back. Thus the movements of the contacts mustbe in preciseaccord with those of the diaphragm, whereby the sound vibrations areprecisely transformed into electrical vibrations on the line.

Our invention consists in the novel devices and combinations of devicesemployed by us in carrying the abovenamed objects into effect, ashereinafter set forth and claimed.

Our invention is illustrated in the accompanying drawings, in whichFigure 1 is a View of a telephone embodying said invention with the casein section; Fig. 2, a perspective view of the back electrode; and Fig. 3illustrates a modified form of the invention.

A is a suitable case provided with mouthpiece A and having binding-posts1 2, to which the wires from battery B and primary of induction-coil Oare connected.

D is the diaphragm, which, as shown, is of metal, though it may be ofmica or other suitable insulating material.

Referring to Figs. 1 and 2, at the center of the diaphragm is secured acontact or electrode a, which is preferably of platinum or faced withthat metal.

E is an arm of any suitable metal, whose lower end rests loosely in amercury-cup b. When placed in contact with the metal diaphragm, asshown, the cup 17 must be of insu= lating material. At its upper end thearm E is forked at c, Fig. 2, and near this end it is preferably facedwith platinum foil d. Projecting from the contact a is a metal stem 6,which passes through the fork of arm E and has upon it a collar f, whichis of insulating material or faced with such material, as at f. Behindthis collar is a thumb-nut g, which permits the position upon the stemof the collar to be adjusted. Connection from bindingpost 1 is by wire 3to the diaphragm, and from binding-post 2 by wire 4 to the mercury incup I). If the'diaphragm is of insulating material, the connection ofwire 3 is directly to contact a, as will be well understood.

It will be seen that arm E rests freely in the mercury-cup and couldmove backward to any extent were it not for the collar f on rod 6. Whenthe diaphragm moves forward, the arm E is thrown back and the desiredseparation of the electrodes is effected. This movement is of course avery slight one, being limited by the end of the arm striking the collarf. When the diaphragm moves back again, bringing rod 6 and collar f withit, said collar of course immediately throws arm E back to its originalposition of contact with electrode a and in readiness to respond fromits normal position to the next vibration. In the normal transmission ofspeech the degree of contact will be varied but not absolutely broken.In the transmission of musical sounds the circuit may be made andbroken. Thus all the movements of the contacts accord exactly with thevibrations of .the diaphragm, and these vibrations are effectivelytransmitted, to be reproduced at the other end of the line by a receiverof any suitable character.

In the form of instrument shown in Fig. '3 mercury-cup b is attacheddirectly to the diaphragm; contact a is upon the diaphragm, and the backcontact is a point h,-carried at the end of a short arm 1', resting inthe mercury. An arm is, rising from the mercury-receptacle, carries ascrew Z, which being situated behind the contact h takes the place ofthe collar f of Fig. 1. Being carried directly by the diaphragm,it movestherewith to bring the contacth back to its normal position with thereturn vibration of the diaphragm.

In both Figs. 1 and 3 the distances between the contacting parts areshown considerably exaggerated. In practice the movement of the upperends of arms E and z' will not be more than one-fiftieth of an inch.

What we claim is 1. In a telephone, the combination, with a diaphragmand an electrode carried thereby,

of a loosely-supported electrode and a limiting-stop therefor rigidlyconnected with the diaphragm, substantially as set forth.

2. In a telephone, the combination, with a diaphragm and an electrodecarried thereby, of a rigid arm extending from said diaphragm, aloosely-supported electrode, and alimitingstop on said arm, said looseelectrode being situated between said diaphragm-electrode and said stop,substantially as set forth.

This specification signed and witnessed 30 this 22d day of December,1885.

THOMAS A. EDISON.

EZRA T. GILLILAND. Witnesses:

JOHN C. TOMLINSON, H. W. SEELY.

